Re: traceroute6: panic: pcb not read locked

On 08/08/15 07:49, Julien Charbon wrote:
> On 08/08/15 05:25, Mark Johnston wrote:
>> On Fri, Aug 07, 2015 at 08:04:01PM -0500, Larry Rosenman wrote:
>>> Trying to debug TimeWarner IPV6 to my HE.NET tunnel, and running traceroute6, 
>>> got the following panic:
>>>
>>> borg.lerctr.org dumped core - see /var/crash/vmcore.0
>>>
>>> Fri Aug  7 19:58:40 CDT 2015
>>>
>>> FreeBSD borg.lerctr.org 11.0-CURRENT FreeBSD 11.0-CURRENT #32 r286338: Wed Aug  5 15:57:55 CDT 2015     root_at_borg.lerctr.org:/usr/obj/usr/src/sys/VT-LER  amd64
>>>
>>> panic: Lock tcp not read locked _at_ /usr/src/sys/netinet/tcp_subr.c:1189
>>>
>>> GNU gdb 6.1.1 [FreeBSD]
>>> Copyright 2004 Free Software Foundation, Inc.
>>> GDB is free software, covered by the GNU General Public License, and you are
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>>> This GDB was configured as "amd64-marcel-freebsd"...
>>>
>>> Unread portion of the kernel message buffer:
>>> panic: Lock tcp not read locked _at_ /usr/src/sys/netinet/tcp_subr.c:1189
>>
>> This appears to be fallout from r286227: the tcpinfo lock assertion in
>> tcp_notify() is too strong, since tcp_notify() can still be called from
>> c with the tcpinfo write lock held.
> 
>  Nice catch, I agree these tcpinfo lock assertion are too strong.  I am
> fixing and testing that as in top of tcp_notify() and tcp_drop(), you
> also need to update also tcp_close() and tcp_detach().

 I pushed a fix in r286443.  I am checking if other paths have the same
issue of kernel assertions being too strict with INP_INFO read/write
lock checks.

 Thanks for the detailed report and patch proposal.

--
Julien